Sunday, September 13, 2015

Plant Stories--The Rise of the Tomato

Tomatoes are everyday foods in the United States. In fact, we often count on them to complete a salad. Years ago, on a business flight, I sat next to a vegetable-broker who told me had made a tidy profit on tomatoes one year when the supplies were limited. He explained that "a salad has to have tomato." Since Americans feel a salad must have a slice of tomato, restaurants will pay whatever it costs for tomatoes. With most vegetables, when the price gets high, they substitute or do without. Knowing that, he was careful to buy tomatoes when a shortage was predicted and happily rode the bidding war that followed.

I do not think it is quite that simple today. Restaurants have created salad options that let them omit tomatoes if they aren't affordable, but it emphasizes the stature of tomatoes in the American diet.

Thus, it seems puzzling that loving tomatoes hasn't been universal.

Tomatoes are classified as Solanum lycopersicum, potato family, Solanaceae. For many years they were in their own genus, Lycopersicon, but more recent study has determined that they are not distinct from other Solanum species, so they were moved into Solanum. That make the genus Solanum quite a genus. There are "1,500-2,000" species, which you can read as "lots of very similar plants." More interesting, it includes three major foods: Solanum lycopersicum, the tomato, Solanum tuberosum, the white potato and Solanum melongena, eggplant, aka aubergine. We eat the fruits of tomato and eggplant, and the underground tubers of potato. There are other Solanum species eaten more regionally (link and link).

tomato flowers

Tomatoes are from South America. The plant thought to be the wild ancestor of the cultivated tomato is found on the edges of the Amazon basin, for example, in Peru, in warm wet tropical conditions.

It was not grown by the Inca. Writers seem puzzled by that, but I think it reflected the growing conditions. The Inca lived in a cool climate at high elevations. Tomatoes, even our domesticated highly-bred ones today, are not frost-tolerant: compare the consequences of the first frost on tomatoes vs cabbage or lettuce. Furthermore, they require such a long growing season that gardeners in the northern half of the United States get the seeds started indoors and transplant 4-6 week old plants outdoors after the last frost. Planting normally in the Andes, the Inca would never have gotten fruit.

Experts agree that tomatoes were domesticated in Mexico.

The Maya and Aztec were great farmers, growing a wide variety of plants. One of them was the tomatillo, Physalis ixocarpa (link and link).

tomatillos

Tomatoes are believed to have appeared in the tomatillo fields as crop weeds. (How they got to central Mexico from the Amazon Basin is a matter of hand-waving. "Carried by birds" is the usual answer. If you've ever seen the flocks of parrots and other fruit-eating birds that plague Central American fields, this seems pretty reasonable.)

The Maya put up with the little tomato plants in among their tomatillos, gradually starting to specifically cultivate tomatoes. By the time Cortez arrived in Mexico in 1519, the Aztecs grew a variety of different tomatoes, of different sizes and shapes.

Not only were tomatoes a late domestication by people who liked tomatillos better, they weren't eaten for themselves by the Aztecs who mainly used them as a minor ingredient in chili sauces.

My perception, that the word tomatillo was a diminutive of tomato, so that tomatillos were named after tomatoes, turns out to be backward. The Aztec word tomatl names something "round and plump." Tomatillos were miltomatl and tomatoes xitomatl. The Conquistators inaccurately picked up the name miltomatl for tomatoes. Spanish speakers reduced it to tomate, and English speakers said tomato.

Tomatillos were the major crop, tomatoes an afterthought, but somehow tomatoes spread across the world and tomatillos did not.

When tomatoes went to Europe, Spaniards and Italians easily grew them and fairly quickly incorporated them into their cuisine.

In northern Europe, North America and Asia, however, eating tomatoes was uncommon in the 16th, 17th and 18th centuries. The problems were various. One problem was that long growing season of tomatoes. In Northern Europe and much of North America, they rarely reached the fruit stage before frost. Greenhouses and an understanding of plant biology developed steadily during the 16th and 17th centuries but could not produce very many tomatoes in a short growing season.

Secondly, tomatoes could not be stored well. Even in 1800, the available preservation methods were salting, sugaring, pickling and drying. Small metal cans that could preserve food were developed in early 1800s but until the 1860s, food in cans was extremely difficult to get out (no can openers!). Home canning (affordable strong glass jars and pressure cookers, for example) became widespread much more recently. Not until the development of canned tomato sauces for home use, about 1920, was there commercial, large-scale production of tomatoes. Fresh tomatoes sold in grocery stories for home use are an even more recent development, needing rapid shipping and refrigeration. Home access was promoted by breeding tomatoes that shipped better--reached the consumer neither crushed nor rotting--which happened at the expense of flavor, leading to our current enthusiasm for heritage tomato varieties.

Finally, people are generally cautious about what they eat. In the 15th century, there were no Solanum species that Europeans routinely ate. The eggplant is from eastern Asia. It came to Arab nations in the Middle East who embraced it and shared it westward across North Africa to Moorish Spain. Christian Europe was fighting the Moors in Spain, not trading with them. The other two Solanum species we commonly eat, tomato and potato, are from the Americas. In 1492, the Christians moved to southern Spain as last Moors were expelled and the Americas were discovered. Strange plants were available to Spanish Christians and then the rest of Europe from both places.

Next time your grocery store offers a fruit or vegetable you don't know, imagine shopping in France about 1550. The Spanish merchant has funny round vegetables for sale that you've never seen before. You don't even know what to call them.

Part of what happened to tomatoes is that they were introduced to northern Europe about the same time as eggplants, and confused with them. Lacking a name, merchants often called them pomi dei Moro, pomme des Mours, or pomi di mori, that is, apple (fruit) of the Moors. Which in France was heard as pomme d'amour, love apple.

But, probably more important, similar-looking species in Europe, for example Solanum dulcamara, bittersweet, Solanum nigrum, black nightshade, and especially deadly nightshade, belladonna, Atropa belladonna, are quite toxic. So the cautious European can be forgiven for not eating fruits that look so much like known poisons. See pictures: bittersweet, black nightshade (UK source), deadly nightshade (nice video). The Illustrated Flora of Britain and the Northern Europe, 1989, writes "Nightshades Solanum...The fruits are generally poisonous." (p. 350) While you can read online of people all over the world eating wild Solanum fruits, there are over 1000 species, some plants do have enough solanine, a toxic alkaloid, to poison you, and plant identification is difficult.

In addition, tomatoes picked up a lot of folk tales quickly. They were thought to be an aphrodisiac, perhaps based on the name love apple. In Victorian England, knowing a fruit was an aphrodisiac would be a definite reason to avoid eating it. Tomatoes also became associated with the occult, perhaps from the relationship to European relatives, for example belladonna, which was commonly linked to witchcraft, perhaps because of the "love apple" name. In fact, the name lycopersicum means "wolf peach" based on the idea, widely held in Germany in the 1600s, that it was used by werewolves.

It was the end of the 19th century and well into the 20th when eating tomatoes rapidly spread through northern Europe, North America and east Asia, to take the place they currently hold as one of the best-known and most widely eaten vegetables. We see tomatoes as very ordinary, but it has not in fact been very long since they were a novelty vegetable.